Method and apparatus for lowering casing into a bore hole



Dec. 31, 1968 M. A. SMITH METHOD AND APPARATUS FOR LOWERINCT CASING INTO A BORE HOLE Filed March 8, 1967 /Z WAZVd/I/A m/z I NVENTOR.

United States Patent METHOD AND APPARATUS FOR LOWERING CASING INTO A BORE HOLE Marvon A. Smith, Ventura, Ca]if., assignor to Reliance Engineering & Development Co., Tehachapi, Calif., a corporation of California Filed Mar. 8, 1967, Ser. No. 621,539

7 Claims. (Cl. 18867) ABSTRACT OF THE DISCLOSURE A layer of sand or other granular material is confined in the annular space between a supporting collar and a casing to be lowered into a bore hole. The sand is allowed to move downward under control out of the lower end of the annular space, thereby permitting the casing to descend by gravity.

Background of the invention This invention relates to a method and apparatus for lowering large diameter easing into a bore hole. A device of this type may be classified as a pipe gripping and lowering device. Heretofore this operation has been accomplished by welding rings on the outer surface of the casing, and then supporting the rings on a plurality of hydraulic jacks, for lowering the casing into the bore hole. For larger and heavier strings of casing, this conventional system is not satisfactory because localized stresses at the points of support become excessive. This invention contemplates the use of a layer of sand, or other granular material, on the outer surface of the casing and confined within a collar supported on the ground. In this way localized stress concentrations are avoided and the load is distributed all around the casing. The sand is allowed to escape at a controlled rate to permit downward movement of the casing by gravity.

Summary Briefly stated, this invention provides a method and apparatus for supporting a casing while lowering it into a bore hole by gravity. Sand, or other granular material, is confined in an annular space between the casing and an encircling stationary collar. Sand is allowed to escape from the lower end of the annular space at a controlled rate, to permit downward movement of the casing by gravity, and the sand thus discharged is returned to the upper end of the annular space.

Brief description of the drawings FIGURE 1 is a sectional elevation showing a preferred embodiment of this invention and showing apparatus for carrying out the method of this invention. Part of the lower portion of the device is shown in elevation.

FIGURE 2 is a sectional plan view taken substantially on the lines 22 as shown in FIGURE 1.

Description of the preferred embodiment Referring to the drawings, the casing 10 comprises a large diameter metal pipe which it to be lowered into a bore hole (not shown) in the earth. Additional sections of easing are added at the upper end as by welding, for example, as the casing is lowered into the bore hole. The upper portion of the casing 10 is encircled by a structure referred to generally as a collar 11. This structure rests on a plurality of hydraulic leveling pads 12 supported on a suitable foundation 13. The collar structure 11 and the casing 10' define an annular space 14 between them, and this space is filled full of granular material such as sand, steel shot, crushed tungsten carbide, or the like. The lower end of the annular space 14 is closed by metal seal rings 15, rubber seal rings 16 and lip-type seal rings 17.

A series of branch passages 20 communicate with the annular space 14 above the position of the seal rings 15, and these passages lead to an annular chamber 21.

The collar structure 11 may be formed of several stationary annular members 23, 24, 25, 26 and 27 which function as an integral unit. The collar structure 11 also includes movable collar sleeves 28 and 29. Sleeve 28 is mounted to telescope over the upper end of the collar section 27 and sleeve 29 is mounted to telescope into the upper end of the collar section 28. Seal rings 31 and 32 are provided to prevent escape of granular material at the telescopic joints.

Hydraulic cylinder assemblies 33 support the collar sleeve 28 with respect to the collar member 27, and hydraulic cylinder assemblies 34 support the collar sleeve 29 on the collar sleeve 28. From this description it will be understood that the collar sleeves 28 and 29 may -be moved under power either up or down between the fully extended position shown in FIGURE 1, and a fully retracted position in which the collar parts 27 and 29 would be in substantial end-to-end engagement, with the seal ring 32 adjacent the seal ring 31.

A plurality of transfer tubes 36 extend from the annular chamber 21 to the hopper 37 at the upper end of the collar structure 11. Air jets 38 fed from a circular manifold pipe 39 direct air upward into the open end of the transfer tubes 36 in order to transfer granular material from the annular chamber 21 to the hopper 37. Suitable controls (not shown) are provided for regulating the fiow of air from the jets 38 into the transfer tubes 36, and suitable hydraulic lines and controls are provided for the hydraulic cylinder assemblies 33 and 34.

In operation, the annular space 14 between the collar structure 11 and the casing 10 is filled with granular material from the hopper 37 to the seal rings 15 and 16. If any granular material should leak past the seal rings 15 and 16, this fact will be evidenced by accumulation of such material in the space 41 via the ports 40. The weight of the casing 10 is transferred through the granular material to the collar structure 11 and then through the leveling pads 12 to the foundation 13. No movement of the casing occurs because it is supported by friction of the granular material in the annular space 14. The air jets 38 are then energized to blow granular material from the chamber 21 up through the transfer tube 36 and into the hopper 37. Granular material then flows through the exit passages 20 from the lower end of the annular space 14 to refill the chamber 21 and the rate of this flow of granular material depends on the rate of transfer of such material from the annular chamber 21 through the transfer tubes 36. While the granular material is passing out of the lower end of the annular space 14 and is being reintroduced into the upper end through passages 42 from the hopper 37, the granular material throughout the length of the annular space 14 moves downward, and the casing 10 moves downward with it.

If the flow of granular material is stopped at the lower end by cutting off the supply of air to the jets 38, the granular material in the annular space 14 stops moving and the casing stops moving. It the casing 10 should continue to move downward, the hydraulic power cylinder assemblies 33 and 34 may be energized to lower their respective collar sleeves 28 and 29, thereby reducing the size of the annular space between the collar sleeve 28 and the casing 10. This action serves to pressurize the granular material in the annular space and set up friction forces which prevent downward movement of the casing 10.

When it is desired to start the casing 10' moving down ward, the hydraulic power cylinder assemblies 33 and 34 are energized to move the collar sleeves 28 and 29 in an upward direction, thereby relieving pressure on the granular material in the annular space 14. Downward movement of the casing 10 then commences, and air jets 38 are energized to transfer the granular material from the chamber 21 to the hopper 37, so that the casing 10 may continue to move downward under control.

I claim:

1. Apparatus for lowering a casing by gravity into a bore hole, comprising, in combination: a collar encircling the casing to define an annular space therebetween, means for supporting the collar, granular material filling said annular space, means for permitting discharge of granular material from the lower end of said annular space to permit gravity descent of the casing relative to the collar, said means controlling the rate of discharge of said granular material.

2. The combination of claim 1 together with means for lifting discharged granular material back into the upper end of said annular space.

3. The combination of claim 1 in which the granular material is sand.

4. Apparatus for controlling the rate of axial movement of a tubular member under an applied force, comprising in combination: a collar encircling the tubular member to define an annular space therebetween, means for supporting the collar against axial movement with the tubular member, granular material filling said annular space,

means for permitting discharge of granular material from one end of the annular space to permit controlled axial movement of the tubular member, said means controlling the rate of discharge of said granular material, and means for returing the discharged granular material to the upper end of said annular space.

5. The method of lowering a casing by gravity into a bore hole, comprising the steps of: introducing granular material into an annular space around a portion of the casing, and permitting granular material to escape from the lower end of the annular space under a controlled rate to permit gravity descent of the casing.

6. The method set forth in claim 5 including returning granular material discharged from the annular space back into the upper end thereof.

7. The method set forth in claim 6 in which the returning of the granular material is accomplished by blowing it upward in a column of air.

References Cited FOREIGN PATENTS 516,116 8/1955 Canada.

GEORGE E. A. HALVOSA, Primary Examiner.

US. Cl. X.R. 

